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Objectives: The improvements in survival with expansion of the survivors’ population, along with evolution of endoscopically-based treatment modalities, have contributed to emphasize the clinical relevance of recurrences in sinonasal cancers. However, at present, literature is scant regarding the pattern of recurrences and the therapeutic strategies available to manage long survivors who experienced single or multiple failures. The aim of the present study was to analyze sinonasal cancers recurrences to provide data regarding rates and patterns of relapse, predictors of failure and prognostic impact of the recurrence. Materials and Methods: All patients receiving multimodal treatments including endoscopic surgery between 1995 and 2021 in three European referral centers were included. Statistical analysis of survival was performed through univariable, multivariable and unidirectional multistate models. Survival after recurrence analysis was implemented for patients experiencing at least one recurrence. Results: The 5- and 10-year recurrence free survival rates were 34.1% and 38.4% for the whole population. With a mean follow-up time of 60 months, a global recurrence rate of 32.9% was observed. The 5- and 10-year survival after recurrence rates were 27.2% and 21.7%, respectively. Incidence and rates of recurrences were significantly associated with histology subtypes. Conclusion: This study provides valuable oncologic outcomes regarding a large homogenous cohort of patients affected by sinonasal malignances treated within a multimodal framework, emphasizing the strong correlation of histologic type with prognosis, as well as with pattern of recurrences.

BACKGROUND: Several microsurgical transcranial approaches (MTAs) and endoscopic transnasal approaches (EEAs) to the anterior cranial fossa (ACF) have been described. OBJECTIVE: To provide a preclinical, quantitative, anatomic, comparative analysis of surgical approaches to the ACF. METHODS: Five alcohol-fixed specimens underwent high-resolution computed tomography. The following approaches were performed on each specimen: EEAs (transcribriform, transtuberculum, and transplanum), anterior MTAs (transfrontal sinus interhemispheric, frontobasal interhemispheric, and subfrontal with unilateral and bilateral frontal craniotomy), and anterolateral MTAs (supraorbital, minipterional, pterional, and frontotemporal orbitozygomatic approach). An optic neuronavigation system and dedicated software (ApproachViewer, part of GTx-Eyes II-UHN) were used to quantify the working volume of each approach and extrapolate the exposure of different ACF regions. Mixed linear models with random intercepts were used for statistical analyses. RESULTS: EEAs offer a large and direct route to the midline region of ACF, whose most anterior structures (ie, crista galli, cribriform plate, and ethmoidal roof) are also well exposed by anterior MTAs, whereas deeper ones (ie, planum sphenoidale and tuberculum sellae) are also well exposed by anterolateral MTAs. The orbital roof region is exposed by both anterolateral and lateral MTAs. The posterolateral region (ie, sphenoid wing and optic canal) is well exposed by anterolateral MTAs. CONCLUSION: Anterior and anterolateral MTAs play a pivotal role in the exposure of most anterior and posterolateral ACF regions, respectively, whereas midline regions are well exposed by EEAs. Furthermore, certain anterolateral approaches may be most useful when involvement of the optic canal and nerves involvement are suspected.

Invasion of the internal carotid artery (ICA) has been historically considered a criterion of non-resectability of skull base cancer (SBC). Patients affected by SBC who underwent surgery including resection of ICA at two tertiary institutions were included. Demographics, oncologic, and surgical information, complications, and survival outcomes were retrospectively reviewed. Survival outcomes were calculated. Ten patients were included. Three surgical approaches (transnasal endoscopic, transorbital, and transpetrosal) were employed to resect the invaded/abutted tract(s) of the ICA. All patients underwent ICA temporary balloon occlusion test. In two patients, an extracranial-to-intracranial arterial bypass was harvested. Major neuromorbidity was observed in two patients. Perioperative mortality of the series was 10.0%. Mean overall survival was 27.2 months, with 2-year overall and progression-free survival rate of 88.9%. ICA resection is feasible as part of the ablation performed for very advanced SBCs. Survival outcomes are acceptable in adequately selected patients.

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Skull base osteomyelitis (SBO) is a potentially life-threatening inflammation of cranial base bony structures of variable origin. Criteria for diagnosis and treatment are still controversial. Demographics, predisposing factors, symptoms, imaging, and clinical, laboratory, histological, and microbiological data of patients managed for SBO at the University Hospital of Brescia (ASST Spedali Civili) between 2002 and 2017 were retrospectively reviewed. Patients were included in different etiological groups. The topographic distribution of magnetic resonance (MR) abnormalities was recorded on a bi-dimensional model of skull base, on which three different patterns of inflammatory changes (edematous, solid, or necrotic) were reported. In patients with a history of radiotherapy, the spatial distribution of SBO was compared with irradiation fields. The association between variables and etiological groups was verified with appropriate statistical tests. A classification tree analysis was performed with the aim of inferring a clinical-radiological diagnostic algorithm for SBO. The study included 47 patients, divided into 5 etiological groups: otogenic (n = 5), radio-induced (n = 16), fungal (n = 14), immune-mediated (n = 6), and idiopathic (n = 6). At MR, five types of topographical distribution were identified (central symmetric, central asymmetric, orbital apex, sinonasal, maxillary). In patients with a history of radiotherapy, the probability to develop SBO was significantly increased in areas receiving the highest radiation dosage. The analysis of patients allowed for design of a classification tree for the diagnosis of SBO. The integration of clinical and radiologic information is an efficient strategy to categorize SBO and potentially guide its complex management.

Transorbital endoscopic approaches are increasing in popularity as they provide corridors to reach various areas of the ventral skull base through the orbit. They can be used either alone or in combination with different approaches when dealing with the pathologies of the skull base. The objective of the current study is to evaluate the surgical anatomy of transorbital endoscopic approaches by cadaver dissections as well as providing objective clinical data on their actual employment and morbidity through a systematic review of the current literature. Four cadaveric specimens were dissected, and step-by-step dissection of each endoscopic transorbital approach was performed to identify the main anatomic landmarks and corridors. A systematic review with pooled analysis of the current literature from January 2000 to April 2020 was performed and the related studies were analyzed. Main anatomical landmarks are presented based on the anatomical study and systematic review of the literature. With emphasis on the specific transorbital approach used, indications, surgical technique, and complications are reviewed through the systematic review of 42 studies (19 in vivo and 23 anatomical dissections) including 193 patients. In conclusion, transorbital endoscopic approaches are promising and appear as feasible techniques for the surgical treatment of skull base lesions. Surgical anatomy of transorbital endoscopic approaches can be mastered through knowledge of a number of anatomical landmarks. Based on data available in the literature, transorbital endoscopic approaches represent an important complementary that should be included in the armamentarium of a skull base team.

BACKGROUND: Only preclinical studies and case reports have described robotic surgery for endoscopic transnasal skull base surgery. OBJECTIVE: To evaluate the role of a novel robotic endoscope holder, developed for transsphenoidal surgery. METHODS: Patients were prospectively enrolled for 3 mo at the Neurosurgery Unit of Brescia. Endoscope Robot® was used to assist during the sphenoidal phase of the approach, tumor removal, and skull base reconstruction. A Likert scale questionnaire was given to all surgeons after each procedure. Patients who underwent robotic-assisted surgery were matched with nonrobotic ones for pathology and type of procedure. All surgical videos were evaluated during bimanual phases. RESULTS: Twenty-one patients underwent robot-assisted, endoscopic transsphenoidal surgery for different pathologies (16 pituitary adenomas, 3 chordomas, 1 craniopharyngioma, 1 pituitary exploration for Cushing disease) for a total of 23 procedures (1 patient underwent 2 endoscopic revisions of a skull base reconstruction). Subjective advantages reported by surgeons included smoothness of movement, image steadiness, and improvement of maneuvers in narrow spaces and with angled endoscopes; as the main limitation, Endoscope Robot® appeared to be relatively heavy during the initial endoscope positioning. A comparative analysis with a historical matched cohort documented similar clinical outcomes, while endoscope lens cleaning and position readjustments were significantly less frequent in robotic procedures. CONCLUSION: Although confirmation in larger studies is needed, Endoscope Robot® was a safe and effective tool, especially advantageous in lengthy interventions through deep and narrow corridors.

Background: Endoscopic transnasal transclival intradural surgery is limited by a high postoperative cerebrospinal fluid leak rate. The aim of this study was to investigate the role of three-dimensional printing to create a personalized, rigid scaffold for clival reconstruction. Methods: Two different types of clivectomy were performed in 5 specimens with the aid of neuronavigation, and 11 clival reconstructions were simulated. They were repaired with polylactide, three-dimensional–printed scaffolds that were manually designed in a computer-aided environment based either on the real or on the predicted defect. Scaffolds were printed with a fused filament fabrication technique and different offsets. They were positioned and fixed either following the gasket seal technique or with screws. Postdissection radiological evaluation of scaffold position was performed in all cases. In 3 specimens, the cerebrospinal fluid leak pressure point was measured immediately after reconstruction. Results: The production process took approximately 30 hours. The designed scaffolds were satisfactory when no offset was added. Wings were added during the design to allow for screw positioning, but broke in 30% of cases. Radiological assessment documented maximal accuracy of scaffold positioning when the scaffold was created on the real defect; accuracy was satisfactory when the predicted clivectomy was performed under neuronavigation guidance. The cerebrospinal fluid leak pressure point was significantly higher when the scaffold was fixed with screws compared with the gasket technique. Conclusions: In this preclinical setting, additive manufacturing allows the creation of customized scaffolds that are effective in reconstructing even large and geometrically complex clival defects.

Background: The endoscope-assisted subtemporal key-hole epidural approach (ESKEA) has been recently described. The aim of this study was to measure working volumes and exposure of key areas of the middle cranial fossa provided by this approach. Methods: Four fresh frozen cadaver heads were dissected to analyze 3 modular corridors (1A, 1B, and 2) harvested through ESKEA. A step-by-step dissection was performed, and key anatomic landmarks were recorded. A GTxEyesII-ApproachViewer was used to quantify the working volume and exposure of 4 different regions (sphenoorbital, parasellar, superior petrous apex, and squamopetrous). For each corridor, 3 incremental degrees of temporal dural retraction (5, 10, and 15 mm) were tested. Results: The working volume of all corridors progressively increased with degree of retraction: Corridors 1A, 1B, and 2 showed a gain in working volume of 21%, 27%, and 19% from 5 mm to 10 mm retraction, respectively, and a gain of 40%, 45%, and 44% from 5 mm to 15 mm retraction, respectively. The sphenoorbital area was exposed (27%−45%) through corridor 1A, and exposure significantly increased with the degree of retraction. Corridor 1B provided optimal exposure of parasellar areas (86%−100%) and superior petrous apex (70%−87%) regardless of the degree of retraction. The squamopetrous area was satisfactorily addressed through corridor 2 (88%) only with the highest degree of retraction. Conclusions: ESKEA can be conceived as a modular approach: the 3 surgical corridors have specific working volumes, which are clearly influenced by the degree of temporal lobe retraction, and provide exposure of different middle cranial fossa areas.

Skull base cephaloceles (SBCs) are defined as herniation of intracranial content through the skull base and are classified based on composition, etiology, and topographic location. Anterior SBCs frequently protrude in the sinonasal cavity, and consequently are at potential risk of infection. Therefore, the current recommendation is to treat SBCs with the primary intent of preventing meningitis, and surgery represents the mainstay of treatment. Anterior SBCs may display a wide spectrum of severity and complexity, and in each case the risks and benefits of surgical approaches are to be carefully weighted based on thorough assessment of symptoms, age, general conditions, location and size of the lesion, as well as expertise of the surgeon. In the last 30 years, the evolution and diffusion of transnasal endoscopic surgery have substantially changed the surgical management of the majority of SBC. In the past, they were treated exclusively with open transcranial approaches that may be burdened by relevant morbidity and risk for severe complications. The transnasal endoscopic corridor now provides easy access to the lesion and different reconstructive strategies using endonasal pedicled flaps, without any external incision, cranioplasty or brain manipulation. However, there are still scenarios in which an exclusive transnasal endoscopic route is contraindicated. The aim of the present review was to provide an overview on the comprehensive management of anterior SBC, with a particular focus on lesions suitable for endoscopic surgery. Furthermore, special aspects of SBC management in children and adults will be highlighted.

Background: Achieving an effective endoscopic skull base reconstruction in case of large dural defects requires specific training and can be extremely challenging. The aim of this study was to describe the development and validation of a preclinical model for cerebrospinal fluid (CSF) leak repair, which can be used for training and to test the mechanical efficacy of endoscopic skull base reconstruction. Methods: Eleven fresh-frozen cadaver heads were dissected. A catheter was inserted in the subdural space via a cervical access, which was sealed with mastic; a vertical graduated tube connected to the catheter measured intracranial pressure (ICP), while stained water was injected intracranially. After endoscopic skull base reconstruction was performed, an expert surgeon assessed its efficacy. ICP was then gradually increased until a leak was evident and CSF leak pressure value was recorded. The correlation between subjective and quantitative evaluations was investigated through Pearson and Spearman correlation tests. Results: The model was successfully tested in 11 specimens. A single, large dural defect was created in each model (transplanum-transtuberculum = 4; transplanum-transtuberculum-transsellar = 3; transclival = 3; transcribriform-transplanum = 1). Skull base reconstruction always comprised a rigid buttress with temporal fascia and/or fat. The CSF leak pressure ranged from 4 to 110 cmH2O. The correlation between expert subjective and quantitative assessment of skull base reconstruction mechanical efficacy was high (r = 0.7; rs = 0.7; p = 0.010 and p = 0.006, respectively). Conclusion: This preclinical model is simple, easily reproducible, and effective in simulating an intraoperative leak and objectively measures the CSF leak pressure point of a skull base reconstruction.

Background: A robotic endoscope holder should theoretically provide various advantages in transnasal endoscopic skull base surgery, but only recently has a robotic system become commercially available. The objective of this study was to provide a preclinical evaluation of potential advantages and surgeon first impression of this robotic hybrid solution. Methods: Thirty skull base surgeons, attending the Joint European Diploma of Endoscopic Skull Base Surgery 2018–2019 in Paris, France, were enrolled. A questionnaire, mainly concerning personal surgical experience and habits, was administered. The test phase consisted of 2 different dry-lab tasks, performed with and without EndoscopeRobot, according to randomization and on 2 different days. A modified NASA Task Load Index test was subsequently administered via e-mail to all participants. Completion times and modified Global Evaluative Assessment of Robotic Skills in Endoscopy scores of the videotaped tasks were recorded. Results: Nineteen otorhinolaryngologic surgeons and 11 neurosurgeons, with different surgical habits and endoscopic experience, were enrolled. No one appeared unfavorable a priori to robotic endoscopic surgery. Although the robot did not provide an advantage in the simple grasping task 1, a trend toward better completion times and efficacy was evident in the bimanual task 2, when performed with the robot and bimanually. According to the modified NASA Task Load Index test, surgeons felt more successful with the robot in task 2, finding it less stressful and mentally demanding. Conclusions: Endoscopic skull base surgeons seem to view a hybrid robotic solution positively. EndoscopeRobot seems to provide a benefit to the single surgeon with experience in bimanual endoscopic surgery. Further preclinical and clinical evaluation of this technology is necessary.

Background: In nasal-ethmoidal malignancies, brain involvement is associated with dismal prognosis. Method: Patients undergoing endoscopic resection with transnasal craniectomy and subpial dissection (ERTC-SD) for brain-invading nasal-ethmoidal cancer between 2008 and 2016 were included. Complications were analyzed in all patients, whereas oncological outcomes only in patients with pathological brain invasion. The prognostic impact of previous treatments, brain edema, and histology was assessed. Hospitalization ratio was calculated. Results: Nineteen patients received ERTC-SD and 11 had pathological-proven brain invasion. Histologies were 6 olfactory neuroblastomas (ONB), 3 neuroendocrine carcinomas, and 2 intestinal-type adenocarcinomas. Mean follow-up was 21.9 months. Three-year overall, local recurrence-free, and distance recurrence-free survivals were 65.5%, 81.8%, and 68.2%, respectively. Overall and distant recurrence-free survivals were significantly better in patients with ONB (P = 0.032 and P = 0.013, respectively). Hospitalization ratio was 4.1%. Complication rate was 10.5%. Conclusion: In selected nasal-ethmoidal tumors with brain invasion, ERTC-SD can provide good local control, satisfactory survival, and limited morbidity.

Background: Several surgical approaches to the parapharyngeal space (PPS) have been proposed. An objective description of advantages and limitations of the surgical routes is lacking. Methods: Ten cadaver heads were dissected using the transnasal (medial, lateral), sublabial, transoral (transpharyngeal, transvestibular, transmandibular), transcervical (transcervical, transparotid, transmandibular, transmastoid), and type C and D infratemporal approaches. Neurovascular and musculoskeletal structures encountered were analyzed. A navigation-based quantification of working volume and exposure of PPS compartments was accomplished. Results: Transnasal approaches exposed the upper PPS, though with limited working volume. Transoral approaches exposed the middle PPS, minimizing neurovascular structures crossed. Only transcervical and skull base approaches exposed the entire PPS, crossing several neurovascular structures. Conclusion: A tentative systematization of the surgical approach(es) to PPS in relation to different targets is provided: unicompartmental resection can be performed with a single, conservative access, whereas multicompartmental dissections frequently require a wider or multiportal approach.

Robotics has already been applied to several surgical fields, but only transoral robotic surgery has a recognized role in skull base surgery. Different preclinical prototypes have been described for endoscopic transnasal skull base surgery (ESBS), but only recently a dedicated, hybrid robotic system has become available for clinical practice.This chapter reviews the use of holders in neurosurgery and skull base surgery, provides an overview of limitations of previous robotic systems that were designed for other surgical applications, describes the different preclinical robotic prototypes that have been developed for ESBS, and reports the initial preclinical and clinical experience with a novel, dedicated, hybrid robotic solution for endoscopic skull base surgery (EndoscopeRobot®, Medineering, Munich, Germany).The era of robotics in skull base surgery is at its dawn, but advantages of the hybrid solution are already evident, though further studies are needed to gain additional data.

Objective: The aim of this study was to assess nasal morbidity of endoscopic transsphenoidal approaches (ETAs) for treatment of sellar and parasellar diseases through evaluation of quality of life (QoL) and nasal function. The impact of different ETAs, according to extent and reconstruction technique, was also studied. Methods: Patients undergoing ETA for treatment of sellar or parasellar lesions were prospectively recruited and examined preoperatively and at 6 months after surgery according to the following workup: nasal endoscopy, rhinomanometry, acoustic rhinometry, University of Pennsylvania Smell Identification Test, Anterior Skull Base Nasal Inventory–12, Sino-nasal Outcome Test–22, and Short-Form Health Survey–36 (SF-36). Results: Of 34 patients initially recruited, 29 completed follow-up examinations. Seven patients (24.14%) developed turbinoseptal synechiae; anterior septal perforations were observed in 3 patients (10.35%). More extended surgical dissection was associated with the presence of postoperative septal perforation and synechiae. No significant difference was noted between preoperative and postoperative results on the University of Pennsylvania Smell Identification Test, acoustic rhinometry, Sino-nasal Outcome Test–22, or Anterior Skull Base Nasal Inventory–12. There was a significant increase in nasal airflow after surgery and improvement of the Short-Form Health Survey–36 score in 4 of 8 domains. Conclusions: The modular ETA technique is associated with minimal morbidity and preserves nasal patency, airflow, and olfactory function. Quality of life is not affected and although small septal perforations and synechiae can be observed, nasal physiology is not compromised. Nonetheless, careful manipulation of sinonasal structures is recommended to minimize postoperative sequelae.

Background: The armamentarium for anterior skull base (ASB) reconstruction includes a variegate spectrum of grafts, endonasal pedicled flaps, regional pedicled flaps, and free flaps, which are selected to face specific scenarios. The use of a vascularized flap in case of large ABS defects ensures an adequate blood supply. The aim of this study was to evaluate the possible role of temporoparietal fascia flap (TPFF) in ASB reconstruction. Methods: Eight fresh-frozen head specimens were dissected to evaluate the adequacy of TPFF and pericranial flap (PF) for the reconstruction of ASB defects. The percentage of coverage of the ASB was calculated for TPFF and PF. An anatomic-radiologic analysis was performed to provide useful practical information for flap harvesting and positioning. Results: The TPFF was easily transposed to the ABS defect through an epidural corridor; the edges of the TPFF were successfully placed in the intradural space, in the epidural space, or on the extracranial surface of the ABS defect. The PF was particularly adequate for median defects, and the TPFF was shown to be useful also in cases with paramedian-supraorbital extension. The median percentage of coverage of the ASB was significantly higher for TPFF (85.1%) than PF (65.7%) (P = 0.018). Conclusions: The supraorbital epidural corridor is a possible novel pathway for transposition of the TPFF for ASB reconstruction. Side-door TPFF was shown to be an ideal choice for large ASB defect with lateral supraorbital extension and could be useful in the scenario of salvage reconstruction for recurrent ABS cerebrospinal fluid leak.

Background: Transnasal endoscopic approaches to the clivus have been established recently. Comparative analyses with classic lateral approaches are limited. In this study, we compared transnasal endoscopic and lateral approaches to the clivus, quantifying the exposure and working volume of each approach in the anatomy laboratory. Methods: High-resolution computed tomography scans were performed on 5 injected specimens (10 sides). In each specimen, transnasal endoscopic approaches (i.e., paraseptal, transrostral, extended transrostral, transethmoidal, and extended transclival without and with intradural hypophysiopexy) and lateral approaches (i.e., retrosigmoid, far-lateral, presigmoid retrolabyrinthine and translabyrinthine) to the clivus were performed. An optic neuronavigation system and dedicated software (ApproachViewer; Guided Therapeutics Program, University Health Network, Toronto, Ontario, Canada) were used to quantify the working volume and exposed clival area of each approach. Statistical evaluation was performed with the Kruskal–Wallis test and Steel–Dwass–Critchlow–Fligner post hoc test. Results: Endoscopic transnasal transclival approaches showed higher working volume and larger clival exposure compared with lateral approaches. Incremental volumetric values were evident for transnasal approaches; presigmoid approaches provided less working volume than retrosigmoid approaches. A transnasal transclival approach with hypophysiopexy provided significant exposure of the upper clivus (84.4%). The transrostral approach was the first transnasal approach providing satisfactory access to the midclivus (66%); retrosigmoid and far-lateral approaches provided exposure of approximately one half of the midclivus. The lower clivus was optimally exposed with endoscopic transclival approaches (83%), whereas access to this region was limited with lateral approaches. Conclusions: This quantitative anatomic study shows that endoscopic transnasal approaches to the clivus pro

Background Endoscopic visualization does not necessarily correspond to an adequate working space. The need for balancing invasiveness and adequacy of sellar tumor exposure has recently led to the description of multiple endoscopic endonasal transsphenoidal approaches. Comparative anatomic data on these variants are lacking. Object We sought to quantitatively compare endoscopic endonasal transsphenoidal approaches to the sella and parasellar region, using the concept of “surgical pyramid.” Methods Four endoscopic transsphenoidal approaches were performed in 10 injected specimens: 1) hemisphenoidotomy; 2) transrostral; 3) extended transrostral (with superior turbinectomy); and 4) extended transrostral with posterior ethmoidectomy. ApproachViewer software (part of GTx-Eyes II, University Health Network, Toronto, Canada) with a dedicated navigation system was used to quantify the surgical pyramid volume, as well as exposure of sellar and parasellar areas. Statistical analyses were performed with Friedman's tests and Nemenyi's procedure. Results Hemisphenoidotomy provided limited exposure of the sellar area and a small working volume. A transrostral approach was necessary to expose the entire sella. Exposure of lateral parasellar areas required superior turbinectomy or posterior ethmoidectomy. The differences between each of the modules was statistically significant. Conclusion The present study validates, from an anatomic point of view, a modular classification of endoscopic endonasal transsphenoidal approaches to the sellar region.

Background: Endoscopic medial maxillectomies (EMMs) are used to optimize exposure of the maxillary sinus and retromaxillary areas. Although in type D EMM (Sturmann-Canfield procedure) the anterior superior alveolar nerve (ASAN) is always at risk of injury, only 29% of patients complained of alveolar process and dental anesthesia. The purpose of this anatomical study is to assess the neural anastomotic network of the ASAN (ASAN-NAN) and describe different extensions of type D EMMs in a preclinical setting. Methods: The ASAN and its medial anastomotic branches (MABs) and lateral anastomotic branches (LABs) were evaluated by cone-beam computerized tomography (CBCT). Five different extensions of type D (D1 to D5) EMMs were identified and nerves at risk of injury in each type were assessed by CBCT. Moreover, quantification of surgical corridors was performed on cadaver heads with a neuronavigation system. Results: Fifty-seven CBCT scans were analyzed. The ASAN would be spared in 16.3% of cases with a type D1 EMM, while it would be injured in the majority of type D2 to D5 resections. At least 1 nerve of the ASAN-NAN was spared in 96.6%, 93%, 74.6%, 0%, and 65.8% of type D1 to D5 EMMs, respectively. Two cadaver heads were dissected and the incremental volume and number of maxillary subsites exposed was assessed in type D1 to D5 EMMs. Conclusion: ASAN function impairment is probably compensated by LABs and MABs. If this hypothesis will be validated in a prospective study on patients, preoperative CBCT evaluation could predict neurological morbidity after type D EMM, and allow tailoring the procedure to minimize impairment of the ASAN-NAN.

Background The nomenclature adopted for endoscopic medial maxillectomies (EMMs) is exceedingly heterogeneous. The aim of this study was to objectively measure surgical exposure in a preclinical anatomic setting to validate a classification for modular EMMs. Materials and Methods Computed tomography was used to scan 6 cadaver heads, and images were uploaded on dedicated software. A neuronavigation system was used to measure areas and volumes of surgical corridors during dissection. Differences of >10% of area exposed and >3 cm3 of volume were considered to define incremental types of EMM. Specific anatomic targets were assessed on the axial and sagittal planes. Influence of anatomic variants on surgical exposure was evaluated. Results There were 4 types of EMMs (A–D), with a transseptal variant for each, identified. In the axial plane, type A exposed the vidian canal and foramen rotundum, type B exposed the foramen ovale and foramen spinosum, and transseptal type C or type D exposed the coronoid process. In the sagittal plane, type A exposed the vidian canal, and type B exposed the foramen ovale and styloid process. Transseptal type C exposed the pterygomaxillary fissure, and type D exposed the inferior border of the lateral pterygoid plate. The nasal floor limits the downward angle in transseptal approaches. The width of the piriform aperture independently influenced surgical volume of types B and C. Conclusions This modular classification of EMMs, based on quantitative analysis in a preclinical setting, should allow for better personalized preoperative surgical planning and provides standardization of nomenclature.

Background and Objective Three-dimensional (3D) endoscopy has been recently introduced in endonasal skull base surgery. Only a relatively limited number of studies have compared it to 2-dimensional, high definition technology. The objective was to compare, in a preclinical setting for endonasal endoscopic surgery, the surgical maneuverability of 2-dimensional, high definition and 3D endoscopy. Methods A group of 68 volunteers, novice and experienced surgeons, were asked to perform 2 tasks, namely simulating grasping and dissection surgical maneuvers, in a model of the nasal cavities. Time to complete the tasks was recorded. A questionnaire to investigate subjective feelings during tasks was filled by each participant. In 25 subjects, the surgeons’ movements were continuously tracked by a magnetic-based neuronavigator coupled with dedicated software (ApproachViewer, part of GTx-UHN) and the recorded trajectories were analyzed by comparing jitter, sum of square differences, and funnel index. Results Total execution time was significantly lower with 3D technology (P < 0.05) in beginners and experts. Questionnaires showed that beginners preferred 3D endoscopy more frequently than experts. A minority (14%) of beginners experienced discomfort with 3D endoscopy. Analysis of jitter showed a trend toward increased effectiveness of surgical maneuvers with 3D endoscopy. Sum of square differences and funnel index analyses documented better values with 3D endoscopy in experts. Conclusions In a preclinical setting for endonasal skull base surgery, 3D technology appears to confer an advantage in terms of time of execution and precision of surgical maneuvers.

Background: In recent years, transorbital endoscopic approaches are increasing in popularity as they provide several corridors to reach lateral areas of the ventral skull base through the orbit. The aim of this study is to investigate the feasibility of the inferolateral transorbital endoscopic approach (ILTEA) by detailing the step-by-step dissection, anatomic landmarks, and target anatomic areas. Methods: Seven cadaveric specimens (14 sides) were dissected in the Laboratory of Endoscopic Anatomy of the University of Brescia. Step-by-step dissection of ILTEA was performed to identify the main anatomic landmarks and corridors. Skin incision, dural incision, and boundaries of craniectomy were measured. Neuronavigation was used to check landmarks, track boundaries of surgical volumes, and measure orbital dislocation. Results: The study on the 14 ILTEAs defined 1 anatomic area ("waterline door") that leads to 4 corridors: Meckel's cave corridor, carotid foramen corridor, petrous corridor, and transdural middle fossa corridor. Crucial anatomic landmarks were identified and analyzed. Orbital dislocation was <10 mm. Conclusions: ILTEA provides the surgeon with a direct route to the region of the "waterline door," lateral areas of the ventral skull base, and middle cranial fossa. In addition, it allows an optimal view of the intracranial and extracranial portions of the maxillary and mandibular nerves. Further anatomic and clinical studies are needed to validate ILTEA in surgical practice.

Background Several endoscopic landmarks for the internal carotid artery (ICA) have been identified, but they have always been proposed in a “static” perspective. The aim of this study was to investigate how the surgical corridor and optical distortion can influence the perception of carotid landmarks in transnasal endoscopic surgery. Methods Computed tomography images of skulls in 20 subjects were analyzed. The petrous carotid angle (PCA) was calculated as the angle between the petrous carotid axis and the coronal plane connecting stylomastoid foramina. The angle of incidence (AI) on the anterior carotid genu of 3 different surgical corridors (contralateral nostril, ipsilateral nostril, and transmaxillary ipsilateral route) was evaluated. PCA, AI, and their differences were studied by Spearman's correlation test. Two cadaver heads were dissected, simulating the studied surgical corridors. The fish-eye effect was empirically quantified. Results Mean PCA was 31° (range, 21–41°). PCA and AI are linked by an inverse proportion relationship. A transmaxillary approach always ensures the highest value of AI on the target. The cadaveric dissection qualitatively confirmed the radiologic data. The fish-eye effect can cause a compression of distance perception as high as 37%. Conclusions The surgical corridor and endoscope optic distortion can influence ICA visualization and the perception of its anatomic landmarks. In a 2-nostril, 4-handed approach, it is advisable to place the endoscope and instrument for dissection in the nostril that is ipsilateral to the lesion. Awareness of the different perspectives and related optical distortions is essential when working in proximity to the ICA.